This invention relates to disposable diapers. More particularly, this invention relates to disposable diapers adapted to be secured in place by adhesive tabs.
Disposable diapers provide substantial advantages in convenience over diapers intended to be laundered and reused, particularly when they are used away from home. In recent years, many different disposable diapers have been proposed and some have been successful in the marketplace. Typical disposable diaper structures comprise a moisture-retaining layer of high liquid-holding capacity and a moisture-impervious backing sheet, generally made of a plastic film such as polyethylene film or the like. Typical disposable diaper structures are shown in U.S. Pat. No. 3,612,055 to Mesek et al. and in U.S. Pat. No. Re. 26,151 to Ducan et al.
As may be seen from the above-cited patents, it is desirable to obviate the problems that are inherent in closure systems which utilize extraneous fasteners such as safety pins, snaps and zippers. To this end adhesive closure systems have presented acceptable solutions.
In order to protect the adhesive surfaces of the tape tabs, usually a cover strip having a release surface is applied over these adhesive surfaces for subsequent removal when the diaper is about to be used. However, such tabs usually project beyond the confines of the diaper to a considerable extent and interfere with the efficient manufacture and packaging of the diaper.
In an attempt to solve the foregoing problems, U.S. Pat. No. 3,776,234 to Hoey proposes to fold the tab over on itself at the diaper's edge and to adhesively attach a portion of the folded-over tab segment to an inwardly-folded margin of the diaper backing sheet in order to keep the tab flat against the diaper and thus from interfering with the manufacturing machinery and with the subsequent folding and packaging operations. This requires that the edge of the diaper backing sheet be folded over to present an attachment surface at the front or inside face of the diaper, and a relatively involved tab design is necessary for this purpose. Also, undesirable tearing of the diaper facing fabric may result if such a tab is inadvertently adhesively attached to the facing fabric of the diaper during manufacture.
U.S. Pat. No. 3,750,669 to DeLuca shows a fastening tape provided with an adhesive end portion which extends beyond a cover strip for the tape and which is attached to a diaper inner covering or facing. However, such an adhesive end portion, when attached to a fibrous, non-woven facing fabric is likely to tear the facing fabric upon separation therefrom.
U.S. Pat. No. 3,646,937 to Gellert shows a fastening tab which is provided with a release surface permanently bonded to the inside surface of the diaper. One of the problems of the Gellert arrangement, as well as all of the other above-cited patents, is that the adhesive tape fasteners are permanently attached to only one surface of the diaper, generally the outside surface of the backing sheet, and thus all of the force exerted on the tape fastener during securement or as the infant moves about is directed to the joint between one end of the tape fastener and the diaper backing sheet.
The tape fastener in U.S Pat. No. 3,848,594 to Buell is attached to both the front and back surfaces of the diaper, but has the disadvantage in that each tape fastener is comprised of at least two separate tape segments which are joined together, thereby adding complexities and expense to the manufacturing process.
The adhesive fastener disclosed in U.S. Pat. No. 3,833,456 to Reed et al. can also be attached to both the front and back surfaces of a substrate. This fastener has the disadvantages, however, of comprising two coextensive webs with each web having an adhesive coating extending along substantially all of one face. The lower web has a release coating along a portion of the opposite face so that a portion of the adhesive coating on the upper web is releasably secured thereto and the rest of the adhesive coating bonds the two webs together. Since two webs are required, the fastener is bulky in the folded configuration, and is relatively expensive to manufacture.